Câu 1:

`(x-y)^2 + 4(x-y) + 4`

`= (x-y)^2 + 2*(x-y)*2 + 2^2`

`= (x-y + 2)^2`

Bài 2:

`a) 16x^2 - 48xz + 36z^2`

`= (4x)^2 - 24x6z + (6z)^2`

`= (4x - 6z)^2`

`b) 81z^4 - 18z^2 + 1`

`= (9z^2)^2 - 29z^21 + 1^2`

`= (9z^2 - 1)^2`

`= ((3z)^2 - 1^2)^2`

`= ((3z - 1)(3z + 1))^2`

`= (3z - 1)^2(3z + 1)^2`

`c) (y+2z)^2 - (y+2z) + 1/4`

`= (y+2z)^2 - 2*(y+2z)*(1/2) + (1/2)^2`

`= (y+2z - 1/2)^2`

Bài 3:

`a, (4x-1)^2 - 121`

`= (4x-1)^2 - 11^2`

`= (4x-1 - 11)(4x-1 + 11)`

`= (4x - 12)(4x + 10)`

`= 4(x - 3)*2(2x + 5)`

`= 8(x - 3)(2x + 5)`

`b, 32x^2 - 2(y-1)^2`

`= 2(16x^2 - (y-1)^2)`

`= 2((4x)^2 - (y-1)^2)`

`= 2(4x - (y-1))(4x + (y-1))`

`= 2(4x - y + 1)(4x + y - 1)`

`c) (3y-2)^2 - 27y^3 = (3y-2)^2 - (3y)^3`

`->` không có công thức phù hợp